Sacramento's clean tech companies more than doubled their revenue over the past three years while providing job growth in a region hard hit by the economic downturn.

In a report released today, the Sacramento Area Regional Technology Alliance said clean tech manufacturers and design companies generated more than $1.5 billion in revenue last year, up from $650 million in 2008.

The industry now employs 2,200 people, an increase of 400 over the past three years, SARTA said.

"It's clear that our focus on growing the clean tech segment of our regional economy is paying off, and we expect to see continued revenue and employment growth moving forward," said Meg Arnold, SARTA's CEO.

Clean tech is still an emerging industry and is relatively small compared to the region's largest private industries, such as health care and real estate. But it is experiencing a steep growth curve. Five years ago, there were only 29 clean tech manufacturers operating in the region. Today there are 96.

The 2012 SARTA CleanStart Progress Report likely understates the impact that green tech is having in the Sacramento region.

The study counted only jobs and sales from companies directly producing solar, wind or other green products or from businesses in the energy efficiency sector.

It did not include employment and sales figures from the industry's supply chain, which includes local metal shops, contractors that install solar panels and makers of sophisticated electronics components that go into the clean tech products.

Greg Simon, chair of SARTA's CleanStart program, said the report's findings track well with a July 2011 study by the Brookings Institution, which ranked Sacramento 12th among the nation's 100 largest metropolitan areas for total number of green jobs.

Some of the growing local companies include Solar Power Inc. of Roseville, which received a $30 million capital infusion from a Chinese solar panel maker and has developed a strong pipeline of new engineering and design work in New Jersey, said Simon.

Another company, Folsom-based data center management firm SynapSense Corp., recently secured $16 million in financing from investors and announced plans to expand in the Asia-Pacific market, he said.

CleanStart, a venture backed by the Sacramento Municipal Utility District, the city of Sacramento, Ernst & Young and other sponsors, has set a long-term goal of attracting 10,000 clean tech jobs and $5 billion in revenues.

"Clearly, we're not there yet," said Simon. "But we've come a long way."